one point two This process is applicable to: a) Ferromagnetic material workpiece.
2.
6.
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7.4.2 rotating magnetic field: the magnetized area shall overlap 15mm each time.
General construction process of magnetic particle testing 1.
Flaw detection can be carried out only after the surface of the inspected workpiece passes the visual inspection.
The flow rate of the magnetic suspension on the detection surface shall not be too fast to prevent the magnetic mark from being damaged by the flowing magnetic suspension.
When the magnetic pole spacing is 200mm, it shall have a lifting force of at least 44N.
Inspection timing Before and after the post weld pressure test.
e) The defective magnetic traces with a length less than 0.5mm shall not be counted, and the size, quantity and parts of all magnetic traces shall be recorded.
During the inspection in both directions, the magnetic lines of force shall be perpendicular to each other.
The magnetization shall be stopped after the suspension is stopped for 1s.
7.
Inspection step 7.1 Before inspection, the surface of type a test piece without artificial defects shall face outward, and it shall be pasted on the surface of the tested workpiece with transparent tape.
During operation, the magnetic suspension shall be applied after it is determined that the whole detection surface is well wetted by the magnetic suspension.
seven point four Magnetization direction and overlap ratio 7.4.1 yoke method: magnetization inspection shall be conducted in at least two different directions on the weld surface.
4.3 sensitivity test piece Select a (30 / 100) 5 、 Working surface requirements: The surface of the inspected workpiece shall be clean and free of grease, rust, oxide scale, coating, flux and welding flying test objects.
8 re inspection: re inspection is required in case of one of the following situations: a) when testing, the sensitivity is unqualified by using the sensitivity piece; b) when the supplier and the buyer have disputes or think there is other needs; c) repaired parts 9.
c) When the included angle between the long axis direction of the defective magnetic trace and the workpiece axis or bus is greater than 30 ℃, it shall be treated as a transverse defect, and others shall be treated as a longitudinal defect.
Flaw detector: Personnel engaged in magnetic particle testing must receive technical training and hold the qualification certificate above II issued by the nondestructive examination committee of the Ministry of labor.
b) Defects with the ratio of length to width greater than 3 show traces, which shall be treated as linear defects.
Note that the tape shall not cover the artificial defects on the test piece.
9.2 the following defects are not allowed to exist a) white spots of any crack b) any transverse defect display C) any linear defect display with a length greater than 1.5mm on the weld d) circular defect display with a single size greater than or equal to 4mm 9.3 The grade evaluation of cumulative length of defect indication shall be based on table 9.3: table 9.3 evaluation dimension 35 × 100 grade Ⅰ < 0.5 < span = "" > Ⅱ≤ 2 Ⅲ≤ 4 Ⅳ≤ 8 Ⅴ is greater than grade Ⅳ 10.
The magnetic suspension must be applied within the power on time, with the power on time of 1-3s.
b) Rotating magnetic field method: de-ed Ⅱ magnetic particle flaw detector is selected.
Executive standard: 4.
d) When two or more defective magnetic traces are on the same straight line and the spacing is less than or equal to 2mm, it shall be treated as one defect, and its length is the sum of the two defects plus the spacing.
b) Alternating current, yoke method or rotating magnetic field wet continuous non fluorescence method.
Selection of equipment, magnetic particle and sensitivity test piece in Chapter IV of JB4730 4.1 equipment a) magnetic particle method: magnetic particle flaw detector with models of b310opd, mp-a3 and de-ed Ⅱ shall be selected.
4.2 magnetic particle The black magnetic paste produced by Shanghai Materials Research Association is used, water is used as the medium, and the concentration of magnetic suspension is 10-20g / 1.
3.
Evaluation of defect display trace grade 9.1 Classification of defect display trace a) in addition to confirming that the display trace is caused by external factors or improper operation, any other display trace equal to or equal to 0.5mm shall be treated as defect display trace.
7.2 in order to increase the detection rate, a layer of contrast enhancer shall be coated on the workpiece surface (including the test piece), and its thickness principal degree shall not be greater than 20 ц m。 7.3 the magnetic suspension shall be applied with a pressure watering can.
Scope of application 1.1 This process is only applicable to the inspection of workpiece surface and near surface defects.
The magnetic spacing shall be 50-200mm, the effective inspection area shall be 50mm on both sides of the two pole connecting line, and the magnetized area within the range shall have 15mm overlap each time.
